Dilatant packaging of downhole components

ABSTRACT

An apparatus for protecting a motion sensitive component used in a borehole includes an enclosure having a chamber receiving the motion sensitive component. An energy absorbing material at least partially surrounds the chamber and a force spreading material at least partially surrounds the chamber. Alternatively, only the force spreading material at least partially surrounds the chamber. The force spreading material may include colloidal particles dispersed in a liquid and whose viscosity increases with shear rate, wherein the particles have a property selected from at least one of: (i) a size no less than 1 μm, (ii) a elongated shape, and (iii) a volume fraction of the colloidal particles in the liquid of at least 30%, and wherein the liquid has a viscosity index of at least 80.

FIELD OF THE DISCLOSURE

This disclosure pertains generally to devices and methods for providingshock and vibration protection for downhole devices.

BACKGROUND OF THE DISCLOSURE

Exploration and production of hydrocarbons generally requires the use ofvarious tools that are lowered into a borehole, such as wirelineassemblies, drilling assemblies, measurement tools and productiondevices (e.g., fracturing tools). Motion sensitive components may bedisposed downhole for various purposes, measuring one or more parametersof interest, control of downhole tools, processing data, communicationwith the surface and storage and analysis of data. Such motion sensitivecomponents often are sensitive to shocks, vibration and other mechanicalstresses. For example, a borehole gravimeter may use a delicate springto enable a gravity measurement, which spring could be broken by shockor vibration prior to its stationary operation at the target depth in awell. Similarly, a subminiature 9-pole mass spectrometer, which issmaller than the size of a thumb, may be made of glass with manyglass-to-metal struts supporting structures within its internal vacuumand this mass spectrometer could be broken while the tool that containsit is being transported to a well location or being run into a wellbefore ever being operated downhole.

In one aspect, the present disclosure addresses the need for enhancedshock and vibration protection for motion sensitive components and othershock and vibration sensitive devices used in a borehole.

SUMMARY OF THE DISCLOSURE

In aspects, the present disclosure provides an apparatus for protectinga motion sensitive component used in a borehole. The apparatus mayinclude an enclosure having a chamber receiving the motion sensitivecomponent, an energy absorbing material at least partially surroundingthe chamber, and a force spreading material at least partiallysurrounding the chamber.

In aspects, the present disclosure also provides an apparatus that hasan enclosure having a chamber receiving the motion sensitive componentand a force spreading material at least partially surrounding thechamber. The force spreading material may include colloidal particlesdispersed in a liquid and whose viscosity increases with shear rate,wherein the particles have a property selected from at least one of: (i)a size no less than 1 (ii) a elongated shape, and (iii) a volumefraction of the colloidal particles in the liquid of at least 30%, andwherein the liquid has a viscosity index of at least 80.

In aspects, the present disclosure further provides a method forapparatus for protecting a motion sensitive component used in aborehole. The method may include the steps of positioning the motionsensitive device in a chamber of an enclosure; at least partiallysurrounding the motion sensitive device with a force spreading material;conveying the motion sensitive device into the borehole; and using themotion sensitive device at a location in the borehole wherein an ambienttemperature is at least 200 degrees Fahrenheit.

Examples of certain features of the disclosure have been summarizedrather broadly in order that the detailed description thereof thatfollows may be better understood and in order that the contributionsthey represent to the art may be appreciated.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed understanding of the present disclosure, reference shouldbe made to the following detailed description of the embodiments, takenin conjunction with the accompanying drawings, in which like elementshave been given like numerals, wherein:

FIG. 1 shows a schematic of a well system that may use one protectiveenclosure according to the present disclosure;

FIG. 2 illustrates one embodiment of an enclosure that uses a forcespreading material and an energy absorbing material to protect motionsensitive components;

FIG. 3 illustrates one embodiment of an enclosure that uses a forcespreading material adapted for high-temperature applications to protectsensitive components; and

FIG. 4A illustrates a graph of the relationship between shear rate andviscosity as a volume fraction of particles in a force spreadingmaterial vary;

FIG. 4B illustrates a graph of the relationship of viscosity and shearrate for different shapes of particles in a force spreading material;and

FIG. 4C illustrates a graph of the relationship of viscosity and shearrate for different sizes of particles in a force spreading material.

DETAILED DESCRIPTION

Operation of tools in a downhole environment exposes such tools tosustained and intense shock and vibration events. These events caninduce failure, fatigue, and accelerated aging in motion sensitivecomponents used in a work string such as a drill string. In aspects, thepresent disclosure provides enclosures and related methods forprotecting motion sensitive components from the energy associated withsuch shock events. In embodiments, the present disclosure providesprotective enclosures that use dilatants. Dilatants are materials whoseviscosity increases with shear rate. The increase in viscosity can be sodramatic that, under the shock of a projectile impact, a putty-likedilatant instantly ‘freezes’ and behaves like a solid, thus spreading ahigh local force over the entire area of the dilatant and therebygreatly reducing any pressure (force per unit area) that is felt by anyobjects being protected behind the dilatant. As discussed in greaterdetail below, some embodiments combine alternating layers of a forcespreading material (e.g., a dilatant) and an energy absorbing material(e.g., silicone gel) to provide enhanced protection against shockevents. Dilatants can be used in military body armor. Silicone gel thatis 2 cm thick can prevent a raw egg from breaking when dropped onto itfrom a height of 60 feet. Other embodiments formulate the dilatant tofunction in a high temperature environment as is found downhole. Suchhigh-temperature embodiments may be used with or without an energyabsorbing layer.

Referring now to FIG. 1, there is shown one illustrative embodiment of adrilling system 10 utilizing a borehole string 12 that may include abottomhole assembly (BHA) 14 for directionally drilling a borehole 16.While a land-based rig is shown, these concepts and the methods areequally applicable to offshore drilling systems. The borehole string 12may be suspended from a rig 20 and may include jointed tubulars orcoiled tubing. In one configuration, the BHA 14 may include a drill bit15, a sensor sub 32, a bidirectional communication and power module(BCPM) 34, a formation evaluation (FE) sub 36, and rotary power devicessuch as drilling motors 38. The sensor sub 32 may include sensors formeasuring near-bit direction (e.g., BHA azimuth and inclination, BHAcoordinates, etc.) and sensors and tools for making rotary directionalsurveys. The system may also include information processing devices suchas a surface controller 50 and/or a downhole controller 42.Communication between the surface and the BHA 14 may use uplinks and/ordownlinks generated by a mud-driven alternator, a mud pulser and/orconveyed using hard wires (e.g., electrical conductors, fiber optics),acoustic signals, EM or RF. It should be appreciated that motionsensitive components can be present throughout the BHA 14.

FIG. 2 illustrates an enclosure 100 for protecting a motion sensitivecomponent 102 used in a downhole environment, such as that shown inFIG. 1. In this non-limiting embodiment, the enclosure 100 includes anouter shell 104 and multiple nested shells 106, 108. The diameters ofthe shells 104, 106, 108 are selected to form annular spaces. An annularspace 110 separating the shell 104 and the shell 106 may be filled withan energy absorbing material 116. An annular space 112 separating theshell 106 and the shell 108 may be filled with a force spreadingmaterial 118. The innermost shell 108 may include a chamber 114 forreceiving the motion sensitive component 102.

The force spreading material 118 may be any material that acts as asolid at high shear rate and a fluid at low shear rate. Such materialsare often referred to as dilatants or “shear thickening fluids”, whichare defined as fluids whose viscosity increases with the shear rate,which makes them non-Newtonian fluids. Generally, these fluids arecomposed of particles suspended in a base liquid. Examples of suchfluids include, but are not limited to, cornstarch in water, quicksand,viscoelastic liquid silicone, etc. The solid particles are ofteninexpensive silica or calcium carbonate particles but they could be madeof other, more expensive materials such as silicon carbide or diamondgrit if one wanted to make the dilatant material more thermallyconductive.

The energy absorbing material 116 may be any material that mechanicallyor chemically absorbs the kinetic energy associated with ashock/vibration event. Such materials may include liquids or gels suchas silicone gel or solids such as elastomeric materials. Common energyabsorbing materials exhibit elastomeric or plastic deformation to absorbenergy and they may include solid rubber, neoprene, silicone, or variousviscoelastic polymers such as polyether-based, polyurethane materials orporous (foam) or structured (hexagonal frame) versions of thesematerials. Recently, 3D printing with silicone-based ink has been usedto make energy absorbing structures whose absorbing properties can beengineered based on their structure. For downhole use, silicone offersthe benefit of having a service temperature to 200 C. Note thatdilatants can absorb some energy and that some energy absorbingmaterials have dilatant properties. However, for the purpose of thisdisclosure, dilatants are defined as materials that are primarilydilatant and energy-absorbing materials are defined as materials thatare primarily energy absorbing.

It should be noted that the enclosure 100 is susceptible to numerousvariants. For example, while the enclosure 100 is depicted as tubular,any other shape (e.g., square, rectangular, etc.) may be used. Also, theshells 104, 106, 108, may be concentrically or eccentrically aligned.Further, while the enclosure 100 is shown as only encircling the motionsensitive component 102, other embodiments may fully enclose the motionsensitive component 102 on all sides. Other variants may be to use morethan one layer of each type of material, e.g., one energy absorbinglayer and two force spreading layers, two of each type of layers, etc.Such multiple layers may or may not be alternating. It should also benoted that the sequence of layers may be reversed; i.e., the outer layermay be the force spreading layer and the inner layer may be the energyabsorbing layer.

Referring to FIG. 3, there is shown another embodiment of an enclosure140 in accordance with the present disclosure. In this non-limitingembodiment, the enclosure 140 includes an outer shell 144 and an innershell 146. The diameters of the shells 144, 146 are selected to formannular spaces. An annular space 150 separating the shell 144 and theshell 146 may be filled with a force spreading material 152. The innershell 146 may include a chamber 152 for receiving the motion sensitivecomponent 102.

The force spreading material 152 may be formulated specifically for usein a relatively hot downhole environment. For purposes of the presentdisclosure, temperatures in excess of about 200 degrees Fahrenheit isconsidered “hot.” The dilatant effect is associated with surfacechemistry of colloidal particles in dispersion. Generally speaking, thedilatant effect tends to diminish in hot ambient environments.Embodiments of the present disclosure enhance the ability of forcespreading material 152 to function in such hot environments by adjustingone or more characteristics of particles suspended in a fluid making upthe force spreading material 152. These characteristics include, but arenot limited to, particle size, shape, and distribution.

For hot environment use, the viscosity versus temperature behavior ofthe base fluid of a dilatant is also important.Usually, the viscosity ofa polymer liquid depends strongly on temperature, which can seriouslyaffect its shear-thickening responses when it is the base fluid intowhich particles are mixed. That is, the critical shear rate for theonset of shear thickening decreases with decreasing temperature andvice-versa. More specifically, the critical shear rate is inverselyproportional to the viscosity of the base fluid into which the particlesare mixed. Therefore, for maximum stability of a dilatant at hightemperatures, it is best to use a base fluid whose viscosity changes aslittle as possible with temperature.

Viscosity Index (VI) is a scale created for automobile motor oils wherethe higher the viscosity index the less the oil's viscosity decreaseswith increasing temperature. A viscosity index of 80 to 110 isconsidered “high” and above “110” is considered “very high”. Varioussilicone liquids (dimethyl-, phenyl-, or halogenated) have a VI of200-650 and perfluoropolyether (PFPE) has a VI of 100-350, polyglycolshave a VI above 200, and polyalphaolefins (PAOs) have a VI of 135-155.For a downhole dilatant, it is best to use a high temperature base fluidhaving a high VI.

Referring to FIGS. 4A-C, there are shown graphs illustrating howparticle characteristics can influence behavior of a dilatant. FIGS.4A-C depict information reported in “A Novel Approach for ArmorApplications of Shear Thickening Fluids in Aviation and DefenseIndustry,” Kushan et al., May 2014.

FIG. 4A illustrates the effect of volume fraction of particles on thechange of viscosity versus shear rate. Shear rate is along the “X” axisand viscosity is along the “Y” axis. Each line represents a dilatantwith a unique volume fraction in a base fluid. Line 160 has the lowestvolume fraction of particles and line 162 has the highest volumefraction of particles. Each line from 160 to 162 has an incrementallyhigher volume fraction of dilatant. As can be seen, the dilatants withthe lower volume fractions, e.g., line 160, have little change inviscosity as shear rate increases whereas dilatants with higher volumefractions, e.g., line 162, exhibits an increase in viscosity after theshear rate passes a particular threshold. By way of illustration, line160 may represent a volume fraction of 25% and line 162 may represent avolume fraction of 45%. Desirable volume fractions may be at least 25%,at least 30%, at least, 40%, or at least 45%.

FIG. 4B illustrates the effect of particle shape on the change ofviscosity versus shear rate. Shear rate increases on an “X” axis andviscosity increases on a “Y” axis. Each line represents a dilatant witha differently shaped particle. Line 170 represents spheroid particles,line 172 represents ovoid particles, line 174 represents platenparticles, and line 176 represents rod/cylindrical particles. As can beseen, the dilatants having spherical particles, e.g., line 170, havelittle change in viscosity as shear rate increases whereas dilatantswith elongated particles, e.g., lines 174, 176, exhibits a steadyincrease in viscosity as shear rate increases. By “elongated,” it ismeant that a body has an asymmetric shape or has different dimensionsalong different axes. The dimensional difference may be one dimension atleast 10%, 25%, or 50% greater than another dimension.

FIG. 4C illustrates the effect of particle size on critical shear rate;i.e., the shear rate at which viscosity changes. Particle size increasesalong the “X” axis and critical shear rate increases along the “Y” axis.As can be seen, an increase in particle size decreases the criticalshear rate. For instance, points 180 representing particles of havingthe largest size have a lower critical shear rate than points 182representing particles having the smallest size. Thus, shear thickeningcan be achieved at lower shear rates by minimizing or eliminatingrelatively smaller particles from a dilatant. For example, particles maybe selected to be no less than 1 μm. Alternatively, a dilatant mayformulate to have at least 60%, 70%, 80%, or 90% of particles greaterthan 1 μm.

In other embodiments, dilatants for high-temperature applications mayuse a fluid selected for such environments. For example, suitableliquids may be liquids that maintain at least 70%, 80%, or 90% of theirviscosity at temperatures in excess of 200 degrees Fahrenheit.

Thus, by appropriately selecting particle properties and fluidproperties, a dilatant may be temperature resistant; i.e., retain aviscosity increase with shear rate even in “hot” ambient environments.This may be done by lowering the value of the shear rate at which shearthickening first occurs, which is the onset value.

While the present teachings have been discussed in the context ofhydrocarbon producing wells, it should be understood that the presentteachings may be applied to geothermal wells, groundwater wells, subseaanalysis, etc.

Also, any conveyance device, other than a drill string, may be used toconvey motion sensitive devices protected according to the presentdisclosure along a borehole. Exemplary non-limiting conveyance devicesinclude casing pipes, wirelines, wire line sondes, slickline sondes,drop shots, downhole subs, BHA's, drill string inserts, modules,internal housings and substrate portions thereof, self-propelledtractors.

While the foregoing disclosure is directed to the one mode embodimentsof the disclosure, various modifications will be apparent to thoseskilled in the art. It is intended that all variations be embraced bythe foregoing disclosure.

We claim:
 1. An apparatus for protecting a motion sensitive componentused in a borehole, comprising: an enclosure having: a chamber receivingthe motion sensitive component; an energy absorbing material at leastpartially surrounding the chamber; and a force spreading material atleast partially surrounding the chamber.
 2. The apparatus according toclaim 1, wherein the chamber includes a plurality of nested shells. 3.The apparatus according to claim 2, wherein the energy absorbingmaterial is disposed between at least two of the plurality of shells. 4.The apparatus according to claim 2, wherein the force spreading materialis disposed between at least two of the plurality of shells.
 5. Theapparatus according to claim 1, wherein the force spreading materialincludes colloidal particles dispersed in a liquid and whose viscosityincreases with shear rate.
 6. The apparatus of claim 5, wherein theparticles are no less than 1 μm.
 7. The apparatus of claim 5, whereinthe particles are elongated.
 8. The apparatus of claim 5, wherein avolume fraction of the particles in the liquid is at least 30%.
 9. Anapparatus for protecting a motion sensitive component used in aborehole, comprising: an enclosure having: a chamber receiving themotion sensitive component; and a force spreading material at leastpartially surrounding the chamber, wherein the force spreading materialincludes colloidal particles dispersed in a liquid and whose viscosityincreases with shear rate, wherein the particles have a propertyselected from at least one of: (i) a size no less than 1 μm, (ii) aelongated shape, and (iii) a volume fraction of the colloidal particlesin the liquid of at least 30%, and wherein the liquid has a viscosityindex of at least
 80. 10. A method for apparatus for protecting a motionsensitive component used in a borehole, comprising: positioning themotion sensitive device in a chamber of an enclosure; at least partiallysurrounding the motion sensitive device with a force spreading material;conveying the motion sensitive device into the borehole; and using themotion sensitive device at a location in the borehole wherein an ambienttemperature is at least 200 degrees Fahrenheit.
 11. The method of claim10, further comprising at least partially surrounding the motionsensitive device with an energy absorbing material.
 12. The method ofclaim 10, wherein the force spreading material includes colloidalparticles dispersed in a liquid and whose viscosity increases with shearrate, and wherein the particles have a property selected from at leastone of: (i) a size no less than 1 μm, (ii) a elongated shape, and (iii)a volume fraction of the colloidal particles in the liquid of at least30%.
 13. The method of claim 10, wherein the force spreading materialincludes colloidal particles dispersed in a liquid and whose viscosityincreases with shear rate, and wherein the particles have: (i) a size noless than 1 um, (ii) a elongated shape, and (iii) a volume fraction ofthe colloidal particles in the liquid of at least 30%, and wherein theliquid has a viscosity index of at least
 80. 14. The method of claim 10,wherein the force spreading material includes colloidal particlesdispersed in a liquid and whose viscosity increases with shear rate, andwherein the liquid has a viscosity index of at least
 80. 15. The methodof claim 14, wherein the fluid is selected from one of: a siliconeliquid, a polyglycol, a perfluoropolyether, and polyalphaolefins.